+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-/*
- * This file is open source software, licensed to you under the terms
- * of the Apache License, Version 2.0 (the "License"). See the NOTICE file
- * distributed with this work for additional information regarding copyright
- * ownership. You may not use this file except in compliance with the License.
- *
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied. See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-/*
- * Copyright (C) 2014 Cloudius Systems, Ltd.
- */
-/*
- * Ceph - scalable distributed file system
- *
- * Copyright (C) 2015 XSky <haomai@xsky.com>
- *
- * Author: Haomai Wang <haomaiwang@gmail.com>
- *
- * This is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License version 2.1, as published by the Free Software
- * Foundation. See file COPYING.
- *
- */
-
-#ifndef CEPH_MSG_STREAM_H_
-#define CEPH_MSG_STREAM_H_
-
-#include <exception>
-#include <cassert>
-
-// A stream<> is the producer side. It may call produce() as long
-// as the returned from the previous invocation is ready.
-// To signify no more data is available, call close().
-//
-// A subscription<> is the consumer side. It is created by a call
-// to stream::listen(). Calling subscription::start(),
-// which registers the data processing callback, starts processing
-// events. It may register for end-of-stream notifications by
-// return the when_done() future, which also delivers error
-// events (as exceptions).
-//
-// The consumer can pause generation of new data by returning
-// positive integer; when it becomes ready, the producer
-// will resume processing.
-
-template <typename... T>
-class subscription;
-
-template <typename... T>
-class stream {
- subscription<T...>* _sub = nullptr;
- int done;
- bool ready;
- public:
- using next_fn = std::function<int (T...)>;
- stream() = default;
- stream(const stream&) = delete;
- stream(stream&&) = delete;
- ~stream() {
- if (_sub) {
- _sub->_stream = nullptr;
- }
- }
-
- void operator=(const stream&) = delete;
- void operator=(stream&&) = delete;
-
- // Returns a subscription that reads value from this
- // stream.
- subscription<T...> listen() {
- return subscription<T...>(this);
- }
-
- // Returns a subscription that reads value from this
- // stream, and also sets up the listen function.
- subscription<T...> listen(next_fn next) {
- auto sub = subscription<T...>(this);
- sub.start(std::move(next));
- return sub;
- }
-
- // Becomes ready when the listener is ready to accept
- // values. Call only once, when beginning to produce
- // values.
- bool started() {
- return ready;
- }
-
- // Produce a value. Call only after started(), and after
- // a previous produce() is ready.
- int produce(T... data) {
- return _sub->_next(std::move(data)...);
- }
-
- // End the stream. Call only after started(), and after
- // a previous produce() is ready. No functions may be called
- // after this.
- void close() {
- done = 1;
- }
-
- // Signal an error. Call only after started(), and after
- // a previous produce() is ready. No functions may be called
- // after this.
- void set_exception(int error) {
- done = error;
- }
- private:
- void start();
- friend class subscription<T...>;
-};
-
-template <typename... T>
-class subscription {
- public:
- using next_fn = typename stream<T...>::next_fn;
- private:
- stream<T...>* _stream;
- next_fn _next;
- private:
- explicit subscription(stream<T...>* s): _stream(s) {
- assert(!_stream->_sub);
- _stream->_sub = this;
- }
-
- public:
- subscription(subscription&& x)
- : _stream(x._stream), _next(std::move(x._next)) {
- x._stream = nullptr;
- if (_stream) {
- _stream->_sub = this;
- }
- }
- ~subscription() {
- if (_stream) {
- _stream->_sub = nullptr;
- }
- }
-
- /// \brief Start receiving events from the stream.
- ///
- /// \param next Callback to call for each event
- void start(std::function<int (T...)> next) {
- _next = std::move(next);
- _stream->ready = true;
- }
-
- // Becomes ready when the stream is empty, or when an error
- // happens (in that case, an exception is held).
- int done() {
- return _stream->done;
- }
-
- friend class stream<T...>;
-};
-
-#endif /* CEPH_MSG_STREAM_H_ */
Code Review / stor4nfv.git / blobdiff